The invention relates to a micromixer for mixing at least two liquid, viscous or gaseous phases, having one inlet passage for each of the phases, a mixing section, in which the phase flows are crossed and divided one or more times, and an outlet passage for the mixture.
Various embodiments of devices for mixing liquid, viscous or gaseous phases are known. The operating principle of these mixers consists in dividing and crossing the two or more phase flows which are to be mixed with one another a number of times, so that an intensively mixed flow of substance is formed at the end of the mixing section. To mix small quantities it is known, for example, to form the mixing section in a thin tube which contains mixing bodies which guide the two phases which are to be mixed in passages which cross one another. However, such tubular mixing sections are less suitable if it is necessary to mix particularly small quantities and, for example, exact temperature control is required.
Therefore, the object of the invention is to design a micromixer of the generic type described in the introduction in such a way that, with little manufacturing outlay, it is possible to construct a mixing section which has a very small receiving volume and allows exact and uniform temperature control in all areas. Moreover, the micromixer is to be easy to clean and is to offer the option of using a very wide range of materials, so that it can be adapted to a very wide range of possible applications.
According to the invention, this object is achieved by the fact that a housing bottom part and a housing top part bear against one another in a sealed manner on connecting surfaces which face towards one another, that the inlet passages and the outlet passage open out into the parting face formed by the connecting surfaces, and that passage grooves, which form the mixing section, are recessed in at least one of the two connecting surfaces.
Since the mixing section comprises exclusively those surfaces of the housing parts which face towards one another and the passage grooves which are recessed therein, there is no need to provide separate mixing bodies. The passage grooves which are recessed in at least one of the two connecting surfaces can be made in any desired surface structure, cross-sectional design and profile adapted to the particular application, using precision-machining processes. Since the machining takes place only in the immediate vicinity of the surface, the manufacturing outlay required for this purpose is relatively low.
The simple, substantially plate-like structure of the two housing parts and, if appropriate, further intermediate housing plates which are arranged between these parts and each have a connecting surface on both sides makes it possible to use a very wide range of materials, the selection of materials as far as possible depending only on the requirements of the substances to be mixed, since manufacturing engineering considerations largely fade into the background.
The seal between the contact surfaces which bear against one another is effected by means of compressive forces, specifically by the precision-machined surfaces and/or seals, for example O-ring seals or flat gaskets, being pressed together. After the micromixer has been opened, all the areas which have come into contact with the substances to be mixed can be cleaned in a simple manner.
Since all the areas of the passages which cross one another in the mixing section as well as any connection grooves are formed in a uniform manner in the connecting surface, the heat transfer conditions in all the passage sections are also entirely uniform. Therefore, completely uniform temperature control can be established in all sections of the passages in the micromixer simply by regulating the temperature of the housing parts. The very small cross section of the channel grooves results in a very high ratio of the passage surface areas to the passage volume, allowing very satisfactory heat exchange to be achieved. This also contributes to increasing the operating reliability and enables exact temperature control.
Preferably, the passage grooves are recessed in only one of the two connecting surfaces which bear against one another. Alternatively, however, it is also possible to recess passage grooves in both connecting surfaces.
According to a preferred embodiment of the invention, the mixing section comprises two passage grooves which run in the form of a wave and cross one another a number of times. This shape of groove is particularly simple to manufacture and results in a substantially equal passage cross section in all areas of the passage, so that there are also constant conditions of heat transfer to the housing parts in all areas. Intensive mixing is achieved in a very small space and with a comparatively short passage length.
Further advantageous configurations of the inventive idea form the subject matter of further subclaims.